Input: add driver for Neonode zForce based touchscreens

This adds a driver for touchscreens using the zforce infrared
technology from Neonode connected via i2c to the host system.

It supports multitouch with up to two fingers and tracking of the
contacts in hardware.

Signed-off-by: Heiko Stuebner <[e-mail]>
Signed-off-by: Dmitry Torokhov <[e-mail]>

drivers/input/touchscreen/Kconfig

···
 	  To compile this driver as a module, choose M here: the
 	  module will be called tps6507x_ts.
 
+config TOUCHSCREEN_ZFORCE
+	tristate "Neonode zForce infrared touchscreens"
+	depends on I2C
+	depends on GPIOLIB
+	help
+	  Say Y here if you have a touchscreen using the zforce
+	  infraread technology from Neonode.
+
+	  If unsure, say N.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called zforce_ts.
+
 endif

drivers/input/touchscreen/Makefile

···
 obj-$(CONFIG_TOUCHSCREEN_WM97XX_ZYLONITE)	+= zylonite-wm97xx.o
 obj-$(CONFIG_TOUCHSCREEN_W90X900)	+= w90p910_ts.o
 obj-$(CONFIG_TOUCHSCREEN_TPS6507X)	+= tps6507x-ts.o
+obj-$(CONFIG_TOUCHSCREEN_ZFORCE)	+= zforce_ts.o

drivers/input/touchscreen/zforce_ts.c

···
+/*
+ * Copyright (C) 2012-2013 MundoReader S.L.
+ * Author: Heiko Stuebner <[e-mail]>
+ *
+ * based in parts on Nook zforce driver
+ *
+ * Copyright (C) 2010 Barnes & Noble, Inc.
+ * Author: Pieter Truter<[e-mail]>
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/module.h>
+#include <linux/hrtimer.h>
+#include <linux/slab.h>
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/i2c.h>
+#include <linux/delay.h>
+#include <linux/gpio.h>
+#include <linux/device.h>
+#include <linux/sysfs.h>
+#include <linux/input/mt.h>
+#include <linux/platform_data/zforce_ts.h>
+
+#define WAIT_TIMEOUT		msecs_to_jiffies(1000)
+
+#define FRAME_START		0xee
+
+/* Offsets of the different parts of the payload the controller sends */
+#define PAYLOAD_HEADER		0
+#define PAYLOAD_LENGTH		1
+#define PAYLOAD_BODY		2
+
+/* Response offsets */
+#define RESPONSE_ID		0
+#define RESPONSE_DATA		1
+
+/* Commands */
+#define COMMAND_DEACTIVATE	0x00
+#define COMMAND_INITIALIZE	0x01
+#define COMMAND_RESOLUTION	0x02
+#define COMMAND_SETCONFIG	0x03
+#define COMMAND_DATAREQUEST	0x04
+#define COMMAND_SCANFREQ	0x08
+#define COMMAND_STATUS		0X1e
+
+/*
+ * Responses the controller sends as a result of
+ * command requests
+ */
+#define RESPONSE_DEACTIVATE	0x00
+#define RESPONSE_INITIALIZE	0x01
+#define RESPONSE_RESOLUTION	0x02
+#define RESPONSE_SETCONFIG	0x03
+#define RESPONSE_SCANFREQ	0x08
+#define RESPONSE_STATUS		0X1e
+
+/*
+ * Notifications are send by the touch controller without
+ * being requested by the driver and include for example
+ * touch indications
+ */
+#define NOTIFICATION_TOUCH		0x04
+#define NOTIFICATION_BOOTCOMPLETE	0x07
+#define NOTIFICATION_OVERRUN		0x25
+#define NOTIFICATION_PROXIMITY		0x26
+#define NOTIFICATION_INVALID_COMMAND	0xfe
+
+#define ZFORCE_REPORT_POINTS		2
+#define ZFORCE_MAX_AREA			0xff
+
+#define STATE_DOWN			0
+#define STATE_MOVE			1
+#define STATE_UP			2
+
+#define SETCONFIG_DUALTOUCH		(1 << 0)
+
+struct zforce_point {
+	int coord_x;
+	int coord_y;
+	int state;
+	int id;
+	int area_major;
+	int area_minor;
+	int orientation;
+	int pressure;
+	int prblty;
+};
+
+/*
+ * @client		the i2c_client
+ * @input		the input device
+ * @suspending		in the process of going to suspend (don't emit wakeup
+ *			events for commands executed to suspend the device)
+ * @suspended		device suspended
+ * @access_mutex	serialize i2c-access, to keep multipart reads together
+ * @command_done	completion to wait for the command result
+ * @command_mutex	serialize commands send to the ic
+ * @command_waiting	the id of the command that that is currently waiting
+ *			for a result
+ * @command_result	returned result of the command
+ */
+struct zforce_ts {
+	struct i2c_client	*client;
+	struct input_dev	*input;
+	const struct zforce_ts_platdata *pdata;
+	char			phys[32];
+
+	bool			suspending;
+	bool			suspended;
+	bool			boot_complete;
+
+	/* Firmware version information */
+	u16			version_major;
+	u16			version_minor;
+	u16			version_build;
+	u16			version_rev;
+
+	struct mutex		access_mutex;
+
+	struct completion	command_done;
+	struct mutex		command_mutex;
+	int			command_waiting;
+	int			command_result;
+};
+
+static int zforce_command(struct zforce_ts *ts, u8 cmd)
+{
+	struct i2c_client *client = ts->client;
+	char buf[3];
+	int ret;
+
+	dev_dbg(&client->dev, "%s: 0x%x\n", __func__, cmd);
+
+	buf[0] = FRAME_START;
+	buf[1] = 1; /* data size, command only */
+	buf[2] = cmd;
+
+	mutex_lock(&ts->access_mutex);
+	ret = i2c_master_send(client, &buf[0], ARRAY_SIZE(buf));
+	mutex_unlock(&ts->access_mutex);
+	if (ret < 0) {
+		dev_err(&client->dev, "i2c send data request error: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int zforce_send_wait(struct zforce_ts *ts, const char *buf, int len)
+{
+	struct i2c_client *client = ts->client;
+	int ret;
+
+	ret = mutex_trylock(&ts->command_mutex);
+	if (!ret) {
+		dev_err(&client->dev, "already waiting for a command\n");
+		return -EBUSY;
+	}
+
+	dev_dbg(&client->dev, "sending %d bytes for command 0x%x\n",
+		buf[1], buf[2]);
+
+	ts->command_waiting = buf[2];
+
+	mutex_lock(&ts->access_mutex);
+	ret = i2c_master_send(client, buf, len);
+	mutex_unlock(&ts->access_mutex);
+	if (ret < 0) {
+		dev_err(&client->dev, "i2c send data request error: %d\n", ret);
+		goto unlock;
+	}
+
+	dev_dbg(&client->dev, "waiting for result for command 0x%x\n", buf[2]);
+
+	if (wait_for_completion_timeout(&ts->command_done, WAIT_TIMEOUT) == 0) {
+		ret = -ETIME;
+		goto unlock;
+	}
+
+	ret = ts->command_result;
+
+unlock:
+	mutex_unlock(&ts->command_mutex);
+	return ret;
+}
+
+static int zforce_command_wait(struct zforce_ts *ts, u8 cmd)
+{
+	struct i2c_client *client = ts->client;
+	char buf[3];
+	int ret;
+
+	dev_dbg(&client->dev, "%s: 0x%x\n", __func__, cmd);
+
+	buf[0] = FRAME_START;
+	buf[1] = 1; /* data size, command only */
+	buf[2] = cmd;
+
+	ret = zforce_send_wait(ts, &buf[0], ARRAY_SIZE(buf));
+	if (ret < 0) {
+		dev_err(&client->dev, "i2c send data request error: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int zforce_resolution(struct zforce_ts *ts, u16 x, u16 y)
+{
+	struct i2c_client *client = ts->client;
+	char buf[7] = { FRAME_START, 5, COMMAND_RESOLUTION,
+			(x & 0xff), ((x >> 8) & 0xff),
+			(y & 0xff), ((y >> 8) & 0xff) };
+
+	dev_dbg(&client->dev, "set resolution to (%d,%d)\n", x, y);
+
+	return zforce_send_wait(ts, &buf[0], ARRAY_SIZE(buf));
+}
+
+static int zforce_scan_frequency(struct zforce_ts *ts, u16 idle, u16 finger,
+				 u16 stylus)
+{
+	struct i2c_client *client = ts->client;
+	char buf[9] = { FRAME_START, 7, COMMAND_SCANFREQ,
+			(idle & 0xff), ((idle >> 8) & 0xff),
+			(finger & 0xff), ((finger >> 8) & 0xff),
+			(stylus & 0xff), ((stylus >> 8) & 0xff) };
+
+	dev_dbg(&client->dev, "set scan frequency to (idle: %d, finger: %d, stylus: %d)\n",
+		idle, finger, stylus);
+
+	return zforce_send_wait(ts, &buf[0], ARRAY_SIZE(buf));
+}
+
+static int zforce_setconfig(struct zforce_ts *ts, char b1)
+{
+	struct i2c_client *client = ts->client;
+	char buf[7] = { FRAME_START, 5, COMMAND_SETCONFIG,
+			b1, 0, 0, 0 };
+
+	dev_dbg(&client->dev, "set config to (%d)\n", b1);
+
+	return zforce_send_wait(ts, &buf[0], ARRAY_SIZE(buf));
+}
+
+static int zforce_start(struct zforce_ts *ts)
+{
+	struct i2c_client *client = ts->client;
+	const struct zforce_ts_platdata *pdata = dev_get_platdata(&client->dev);
+	int ret;
+
+	dev_dbg(&client->dev, "starting device\n");
+
+	ret = zforce_command_wait(ts, COMMAND_INITIALIZE);
+	if (ret) {
+		dev_err(&client->dev, "Unable to initialize, %d\n", ret);
+		return ret;
+	}
+
+	ret = zforce_resolution(ts, pdata->x_max, pdata->y_max);
+	if (ret) {
+		dev_err(&client->dev, "Unable to set resolution, %d\n", ret);
+		goto error;
+	}
+
+	ret = zforce_scan_frequency(ts, 10, 50, 50);
+	if (ret) {
+		dev_err(&client->dev, "Unable to set scan frequency, %d\n",
+			ret);
+		goto error;
+	}
+
+	if (zforce_setconfig(ts, SETCONFIG_DUALTOUCH)) {
+		dev_err(&client->dev, "Unable to set config\n");
+		goto error;
+	}
+
+	/* start sending touch events */
+	ret = zforce_command(ts, COMMAND_DATAREQUEST);
+	if (ret) {
+		dev_err(&client->dev, "Unable to request data\n");
+		goto error;
+	}
+
+	/*
+	 * Per NN, initial cal. take max. of 200msec.
+	 * Allow time to complete this calibration
+	 */
+	msleep(200);
+
+	return 0;
+
+error:
+	zforce_command_wait(ts, COMMAND_DEACTIVATE);
+	return ret;
+}
+
+static int zforce_stop(struct zforce_ts *ts)
+{
+	struct i2c_client *client = ts->client;
+	int ret;
+
+	dev_dbg(&client->dev, "stopping device\n");
+
+	/* Deactivates touch sensing and puts the device into sleep. */
+	ret = zforce_command_wait(ts, COMMAND_DEACTIVATE);
+	if (ret != 0) {
+		dev_err(&client->dev, "could not deactivate device, %d\n",
+			ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int zforce_touch_event(struct zforce_ts *ts, u8 *payload)
+{
+	struct i2c_client *client = ts->client;
+	const struct zforce_ts_platdata *pdata = dev_get_platdata(&client->dev);
+	struct zforce_point point;
+	int count, i, num = 0;
+
+	count = payload[0];
+	if (count > ZFORCE_REPORT_POINTS) {
+		dev_warn(&client->dev, "to many coordinates %d, expected max %d\n",
+			 count, ZFORCE_REPORT_POINTS);
+		count = ZFORCE_REPORT_POINTS;
+	}
+
+	for (i = 0; i < count; i++) {
+		point.coord_x =
+			payload[9 * i + 2] << 8 | payload[9 * i + 1];
+		point.coord_y =
+			payload[9 * i + 4] << 8 | payload[9 * i + 3];
+
+		if (point.coord_x > pdata->x_max ||
+		    point.coord_y > pdata->y_max) {
+			dev_warn(&client->dev, "coordinates (%d,%d) invalid\n",
+				point.coord_x, point.coord_y);
+			point.coord_x = point.coord_y = 0;
+		}
+
+		point.state = payload[9 * i + 5] & 0x03;
+		point.id = (payload[9 * i + 5] & 0xfc) >> 2;
+
+		/* determine touch major, minor and orientation */
+		point.area_major = max(payload[9 * i + 6],
+					  payload[9 * i + 7]);
+		point.area_minor = min(payload[9 * i + 6],
+					  payload[9 * i + 7]);
+		point.orientation = payload[9 * i + 6] > payload[9 * i + 7];
+
+		point.pressure = payload[9 * i + 8];
+		point.prblty = payload[9 * i + 9];
+
+		dev_dbg(&client->dev,
+			"point %d/%d: state %d, id %d, pressure %d, prblty %d, x %d, y %d, amajor %d, aminor %d, ori %d\n",
+			i, count, point.state, point.id,
+			point.pressure, point.prblty,
+			point.coord_x, point.coord_y,
+			point.area_major, point.area_minor,
+			point.orientation);
+
+		/* the zforce id starts with "1", so needs to be decreased */
+		input_mt_slot(ts->input, point.id - 1);
+
+		input_mt_report_slot_state(ts->input, MT_TOOL_FINGER,
+						point.state != STATE_UP);
+
+		if (point.state != STATE_UP) {
+			input_report_abs(ts->input, ABS_MT_POSITION_X,
+					 point.coord_x);
+			input_report_abs(ts->input, ABS_MT_POSITION_Y,
+					 point.coord_y);
+			input_report_abs(ts->input, ABS_MT_TOUCH_MAJOR,
+					 point.area_major);
+			input_report_abs(ts->input, ABS_MT_TOUCH_MINOR,
+					 point.area_minor);
+			input_report_abs(ts->input, ABS_MT_ORIENTATION,
+					 point.orientation);
+			num++;
+		}
+	}
+
+	input_mt_sync_frame(ts->input);
+
+	input_mt_report_finger_count(ts->input, num);
+
+	input_sync(ts->input);
+
+	return 0;
+}
+
+static int zforce_read_packet(struct zforce_ts *ts, u8 *buf)
+{
+	struct i2c_client *client = ts->client;
+	int ret;
+
+	mutex_lock(&ts->access_mutex);
+
+	/* read 2 byte message header */
+	ret = i2c_master_recv(client, buf, 2);
+	if (ret < 0) {
+		dev_err(&client->dev, "error reading header: %d\n", ret);
+		goto unlock;
+	}
+
+	if (buf[PAYLOAD_HEADER] != FRAME_START) {
+		dev_err(&client->dev, "invalid frame start: %d\n", buf[0]);
+		ret = -EIO;
+		goto unlock;
+	}
+
+	if (buf[PAYLOAD_LENGTH] <= 0 || buf[PAYLOAD_LENGTH] > 255) {
+		dev_err(&client->dev, "invalid payload length: %d\n",
+			buf[PAYLOAD_LENGTH]);
+		ret = -EIO;
+		goto unlock;
+	}
+
+	/* read the message */
+	ret = i2c_master_recv(client, &buf[PAYLOAD_BODY], buf[PAYLOAD_LENGTH]);
+	if (ret < 0) {
+		dev_err(&client->dev, "error reading payload: %d\n", ret);
+		goto unlock;
+	}
+
+	dev_dbg(&client->dev, "read %d bytes for response command 0x%x\n",
+		buf[PAYLOAD_LENGTH], buf[PAYLOAD_BODY]);
+
+unlock:
+	mutex_unlock(&ts->access_mutex);
+	return ret;
+}
+
+static void zforce_complete(struct zforce_ts *ts, int cmd, int result)
+{
+	struct i2c_client *client = ts->client;
+
+	if (ts->command_waiting == cmd) {
+		dev_dbg(&client->dev, "completing command 0x%x\n", cmd);
+		ts->command_result = result;
+		complete(&ts->command_done);
+	} else {
+		dev_dbg(&client->dev, "command %d not for us\n", cmd);
+	}
+}
+
+static irqreturn_t zforce_interrupt(int irq, void *dev_id)
+{
+	struct zforce_ts *ts = dev_id;
+	struct i2c_client *client = ts->client;
+	const struct zforce_ts_platdata *pdata = dev_get_platdata(&client->dev);
+	int ret;
+	u8 payload_buffer[512];
+	u8 *payload;
+
+	/*
+	 * When suspended, emit a wakeup signal if necessary and return.
+	 * Due to the level-interrupt we will get re-triggered later.
+	 */
+	if (ts->suspended) {
+		if (device_may_wakeup(&client->dev))
+			pm_wakeup_event(&client->dev, 500);
+		msleep(20);
+		return IRQ_HANDLED;
+	}
+
+	dev_dbg(&client->dev, "handling interrupt\n");
+
+	/* Don't emit wakeup events from commands run by zforce_suspend */
+	if (!ts->suspending && device_may_wakeup(&client->dev))
+		pm_stay_awake(&client->dev);
+
+	while (!gpio_get_value(pdata->gpio_int)) {
+		ret = zforce_read_packet(ts, payload_buffer);
+		if (ret < 0) {
+			dev_err(&client->dev, "could not read packet, ret: %d\n",
+				ret);
+			break;
+		}
+
+		payload =  &payload_buffer[PAYLOAD_BODY];
+
+		switch (payload[RESPONSE_ID]) {
+		case NOTIFICATION_TOUCH:
+			/*
+			 * Always report touch-events received while
+			 * suspending, when being a wakeup source
+			 */
+			if (ts->suspending && device_may_wakeup(&client->dev))
+				pm_wakeup_event(&client->dev, 500);
+			zforce_touch_event(ts, &payload[RESPONSE_DATA]);
+			break;
+
+		case NOTIFICATION_BOOTCOMPLETE:
+			ts->boot_complete = payload[RESPONSE_DATA];
+			zforce_complete(ts, payload[RESPONSE_ID], 0);
+			break;
+
+		case RESPONSE_INITIALIZE:
+		case RESPONSE_DEACTIVATE:
+		case RESPONSE_SETCONFIG:
+		case RESPONSE_RESOLUTION:
+		case RESPONSE_SCANFREQ:
+			zforce_complete(ts, payload[RESPONSE_ID],
+					payload[RESPONSE_DATA]);
+			break;
+
+		case RESPONSE_STATUS:
+			/*
+			 * Version Payload Results
+			 * [2:major] [2:minor] [2:build] [2:rev]
+			 */
+			ts->version_major = (payload[RESPONSE_DATA + 1] << 8) |
+						payload[RESPONSE_DATA];
+			ts->version_minor = (payload[RESPONSE_DATA + 3] << 8) |
+						payload[RESPONSE_DATA + 2];
+			ts->version_build = (payload[RESPONSE_DATA + 5] << 8) |
+						payload[RESPONSE_DATA + 4];
+			ts->version_rev   = (payload[RESPONSE_DATA + 7] << 8) |
+						payload[RESPONSE_DATA + 6];
+			dev_dbg(&ts->client->dev, "Firmware Version %04x:%04x %04x:%04x\n",
+				ts->version_major, ts->version_minor,
+				ts->version_build, ts->version_rev);
+
+			zforce_complete(ts, payload[RESPONSE_ID], 0);
+			break;
+
+		case NOTIFICATION_INVALID_COMMAND:
+			dev_err(&ts->client->dev, "invalid command: 0x%x\n",
+				payload[RESPONSE_DATA]);
+			break;
+
+		default:
+			dev_err(&ts->client->dev, "unrecognized response id: 0x%x\n",
+				payload[RESPONSE_ID]);
+			break;
+		}
+	}
+
+	if (!ts->suspending && device_may_wakeup(&client->dev))
+		pm_relax(&client->dev);
+
+	dev_dbg(&client->dev, "finished interrupt\n");
+
+	return IRQ_HANDLED;
+}
+
+static int zforce_input_open(struct input_dev *dev)
+{
+	struct zforce_ts *ts = input_get_drvdata(dev);
+	int ret;
+
+	ret = zforce_start(ts);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static void zforce_input_close(struct input_dev *dev)
+{
+	struct zforce_ts *ts = input_get_drvdata(dev);
+	struct i2c_client *client = ts->client;
+	int ret;
+
+	ret = zforce_stop(ts);
+	if (ret)
+		dev_warn(&client->dev, "stopping zforce failed\n");
+
+	return;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int zforce_suspend(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct zforce_ts *ts = i2c_get_clientdata(client);
+	struct input_dev *input = ts->input;
+	int ret = 0;
+
+	mutex_lock(&input->mutex);
+	ts->suspending = true;
+
+	/*
+	 * When configured as a wakeup source device should always wake
+	 * the system, therefore start device if necessary.
+	 */
+	if (device_may_wakeup(&client->dev)) {
+		dev_dbg(&client->dev, "suspend while being a wakeup source\n");
+
+		/* Need to start device, if not open, to be a wakeup source. */
+		if (!input->users) {
+			ret = zforce_start(ts);
+			if (ret)
+				goto unlock;
+		}
+
+		enable_irq_wake(client->irq);
+	} else if (input->users) {
+		dev_dbg(&client->dev, "suspend without being a wakeup source\n");
+
+		ret = zforce_stop(ts);
+		if (ret)
+			goto unlock;
+
+		disable_irq(client->irq);
+	}
+
+	ts->suspended = true;
+
+unlock:
+	ts->suspending = false;
+	mutex_unlock(&input->mutex);
+
+	return ret;
+}
+
+static int zforce_resume(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct zforce_ts *ts = i2c_get_clientdata(client);
+	struct input_dev *input = ts->input;
+	int ret = 0;
+
+	mutex_lock(&input->mutex);
+
+	ts->suspended = false;
+
+	if (device_may_wakeup(&client->dev)) {
+		dev_dbg(&client->dev, "resume from being a wakeup source\n");
+
+		disable_irq_wake(client->irq);
+
+		/* need to stop device if it was not open on suspend */
+		if (!input->users) {
+			ret = zforce_stop(ts);
+			if (ret)
+				goto unlock;
+		}
+	} else if (input->users) {
+		dev_dbg(&client->dev, "resume without being a wakeup source\n");
+
+		enable_irq(client->irq);
+
+		ret = zforce_start(ts);
+		if (ret < 0)
+			goto unlock;
+	}
+
+unlock:
+	mutex_unlock(&input->mutex);
+
+	return ret;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(zforce_pm_ops, zforce_suspend, zforce_resume);
+
+static void zforce_reset(void *data)
+{
+	struct zforce_ts *ts = data;
+
+	gpio_set_value(ts->pdata->gpio_rst, 0);
+}
+
+static int zforce_probe(struct i2c_client *client,
+			const struct i2c_device_id *id)
+{
+	const struct zforce_ts_platdata *pdata = dev_get_platdata(&client->dev);
+	struct zforce_ts *ts;
+	struct input_dev *input_dev;
+	int ret;
+
+	if (!pdata)
+		return -EINVAL;
+
+	ts = devm_kzalloc(&client->dev, sizeof(struct zforce_ts), GFP_KERNEL);
+	if (!ts)
+		return -ENOMEM;
+
+	ret = devm_gpio_request_one(&client->dev, pdata->gpio_int, GPIOF_IN,
+				    "zforce_ts_int");
+	if (ret) {
+		dev_err(&client->dev, "request of gpio %d failed, %d\n",
+			pdata->gpio_int, ret);
+		return ret;
+	}
+
+	ret = devm_gpio_request_one(&client->dev, pdata->gpio_rst,
+				    GPIOF_OUT_INIT_LOW, "zforce_ts_rst");
+	if (ret) {
+		dev_err(&client->dev, "request of gpio %d failed, %d\n",
+			pdata->gpio_rst, ret);
+		return ret;
+	}
+
+	ret = devm_add_action(&client->dev, zforce_reset, ts);
+	if (ret) {
+		dev_err(&client->dev, "failed to register reset action, %d\n",
+			ret);
+		return ret;
+	}
+
+	snprintf(ts->phys, sizeof(ts->phys),
+		 "%s/input0", dev_name(&client->dev));
+
+	input_dev = devm_input_allocate_device(&client->dev);
+	if (!input_dev) {
+		dev_err(&client->dev, "could not allocate input device\n");
+		return -ENOMEM;
+	}
+
+	mutex_init(&ts->access_mutex);
+	mutex_init(&ts->command_mutex);
+
+	ts->pdata = pdata;
+	ts->client = client;
+	ts->input = input_dev;
+
+	input_dev->name = "Neonode zForce touchscreen";
+	input_dev->phys = ts->phys;
+	input_dev->id.bustype = BUS_I2C;
+
+	input_dev->open = zforce_input_open;
+	input_dev->close = zforce_input_close;
+
+	__set_bit(EV_KEY, input_dev->evbit);
+	__set_bit(EV_SYN, input_dev->evbit);
+	__set_bit(EV_ABS, input_dev->evbit);
+
+	/* For multi touch */
+	input_set_abs_params(input_dev, ABS_MT_POSITION_X, 0,
+			     pdata->x_max, 0, 0);
+	input_set_abs_params(input_dev, ABS_MT_POSITION_Y, 0,
+			     pdata->y_max, 0, 0);
+
+	input_set_abs_params(input_dev, ABS_MT_TOUCH_MAJOR, 0,
+			     ZFORCE_MAX_AREA, 0, 0);
+	input_set_abs_params(input_dev, ABS_MT_TOUCH_MINOR, 0,
+			     ZFORCE_MAX_AREA, 0, 0);
+	input_set_abs_params(input_dev, ABS_MT_ORIENTATION, 0, 1, 0, 0);
+	input_mt_init_slots(input_dev, ZFORCE_REPORT_POINTS, INPUT_MT_DIRECT);
+
+	input_set_drvdata(ts->input, ts);
+
+	init_completion(&ts->command_done);
+
+	/*
+	 * The zforce pulls the interrupt low when it has data ready.
+	 * After it is triggered the isr thread runs until all the available
+	 * packets have been read and the interrupt is high again.
+	 * Therefore we can trigger the interrupt anytime it is low and do
+	 * not need to limit it to the interrupt edge.
+	 */
+	ret = devm_request_threaded_irq(&client->dev, client->irq, NULL,
+					zforce_interrupt,
+					IRQF_TRIGGER_LOW | IRQF_ONESHOT,
+					input_dev->name, ts);
+	if (ret) {
+		dev_err(&client->dev, "irq %d request failed\n", client->irq);
+		return ret;
+	}
+
+	i2c_set_clientdata(client, ts);
+
+	/* let the controller boot */
+	gpio_set_value(pdata->gpio_rst, 1);
+
+	ts->command_waiting = NOTIFICATION_BOOTCOMPLETE;
+	if (wait_for_completion_timeout(&ts->command_done, WAIT_TIMEOUT) == 0)
+		dev_warn(&client->dev, "bootcomplete timed out\n");
+
+	/* need to start device to get version information */
+	ret = zforce_command_wait(ts, COMMAND_INITIALIZE);
+	if (ret) {
+		dev_err(&client->dev, "unable to initialize, %d\n", ret);
+		return ret;
+	}
+
+	/* this gets the firmware version among other informations */
+	ret = zforce_command_wait(ts, COMMAND_STATUS);
+	if (ret < 0) {
+		dev_err(&client->dev, "couldn't get status, %d\n", ret);
+		zforce_stop(ts);
+		return ret;
+	}
+
+	/* stop device and put it into sleep until it is opened */
+	ret = zforce_stop(ts);
+	if (ret < 0)
+		return ret;
+
+	device_set_wakeup_capable(&client->dev, true);
+
+	ret = input_register_device(input_dev);
+	if (ret) {
+		dev_err(&client->dev, "could not register input device, %d\n",
+			ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static struct i2c_device_id zforce_idtable[] = {
+	{ "zforce-ts", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, zforce_idtable);
+
+static struct i2c_driver zforce_driver = {
+	.driver = {
+		.owner	= THIS_MODULE,
+		.name	= "zforce-ts",
+		.pm	= &zforce_pm_ops,
+	},
+	.probe		= zforce_probe,
+	.id_table	= zforce_idtable,
+};
+
+module_i2c_driver(zforce_driver);
+
+MODULE_AUTHOR("Heiko Stuebner <[e-mail]>");
+MODULE_DESCRIPTION("zForce TouchScreen Driver");
+MODULE_LICENSE("GPL");

include/linux/platform_data/zforce_ts.h

···
+/* drivers/input/touchscreen/zforce.c
+ *
+ * Copyright (C) 2012-2013 MundoReader S.L.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef _LINUX_INPUT_ZFORCE_TS_H
+#define _LINUX_INPUT_ZFORCE_TS_H
+
+struct zforce_ts_platdata {
+	int gpio_int;
+	int gpio_rst;
+
+	unsigned int x_max;
+	unsigned int y_max;
+};
+
+#endif /* _LINUX_INPUT_ZFORCE_TS_H */